Tag: Bats

Posted on

Bear Lake Limestone

Bear Lake Limestone: Pale Blue Bear Lake from the Shore, Courtesy & Copyright Mary Heers, Photographer
Pale Blue Bear Lake from the Shore
Courtesy & Copyright Mary Heers, Photographer

Blue Sky Reflected on the Water of Bear Lake, Courtesy & Copyright Mary Heers, Photographer Blue Sky Reflected on the Water of Bear Lake
Courtesy & Copyright Mary Heers, Photographer

Stalagmites in Minnetonka Cave, St Charles Canyon, West of Bear Lake, Courtesy & Copyright Mary Heers, Photographer Stalagmites in Minnetonka Cave, St Charles Canyon, West of Bear Lake
Courtesy & Copyright Mary Heers, Photographer

Soda Straw Stalactites in Minnetonka Cave, St Charles Canyon, West of Bear Lake, Courtesy & Copyright Mary Heers, Photographer Soda Straw Stalactites in Minnetonka Cave, St Charles Canyon, West of Bear Lake
Courtesy & Copyright Mary Heers, Photographer

Small Ribbon Stalactites in Minnetonka Cave, St Charles Canyon, West of Bear Lake, Courtesy & Copyright Mary Heers, Photographer Small Ribbon Stalactites in Minnetonka Cave, St Charles Canyon, West of Bear Lake
Courtesy & Copyright Mary Heers, Photographer

Stalagmite in Minnetonka Cave, St Charles Canyon, West of Bear Lake, Courtesy & Copyright Mary Heers, Photographer Stalagmite in Minnetonka Cave, St Charles Canyon, West of Bear Lake
Courtesy & Copyright Mary Heers, Photographer

If you stop at the overlook above Bear Lake on a sunny summer day, you may be as surprised as I was to find out that the gray limestone rocks in Logan Canyon are responsible for the brilliant blue color of the lake. Among the wealth of information displayed at the overlook is the fact that as rainwater and melting snow seeps down through the limestone, it picks up tiny bits of calcium. This calcium in the lake water acts as “millions of microscopic mirrors” that reflect the exact color of the blue sky.

Once I started thinking about water seeping through this limestone, I signed up to take a tour of the Minnetonka Caves located above St Charles towards the northern side of the lake. Millions of years ago, water began to seep into small fissures in the rock, widening into larger cracks and puddling into low spots. When the water table dropped, the water drained away, leaving large crevices and 9 open rooms behind.

The cave was discovered in 1906 by Edward Arnell, who was out hunting and shot a grouse that fell just over a nearby ledge. He scrambled down to retrieve the bird, and then he felt it: cold air. Pushing aside some rocks he found the hole in the hillside – just large enough for a man to crawl through.

He found a bear skeleton near the entrance, but no sign that humans had ever been inside the cave before.

In 1939 the WPA went to work enlarging the entrance. They chiseled 444 steps into the rock and paved a rough path between the rooms.

Today the cave is managed by the Montpelier Ranger Station, who lead tours into the cave in the summer months. When my turn came, I slipped on my hoodie, grabbed the ice cold railing, and started down the slippery steps with my group. A generator was keeping the path dimly lit while spotlighting some of the drip formations. I was expecting stalactites and stalagmites, but I was delighted to also see sheets of dripping water frozen in time and looking very much like drapes. Hollow tubes called “soda straws” hung from the ceiling.

About half a mile into the cave our guide stopped us and turned us around. The rest of the cave, he said, was reserved for the five species of bats that spend the winter here. The cave stays at a cool 40 degrees year round – a perfect temperature for hibernating bats who will lower their temperature to near freezing, slow their heartbeat from 200 to 10 beats a minute, and only take a breath every few minutes.

I guess I’ve always envied hibernating mammals like bats and bears who go to sleep fat, doze through the winter, and wake up thin in the spring.

Before we started back up the 444 steps, our guide had one more lesson for us. He turned off the lights to allow us to experience a few moments of utter darkness.

Just as the lights came back on, a drip of cold water fell from the cave ceiling and landed on me. I felt like I’d been kissed.

This is Mary Heers and I’m Wild About Utah.

Credits:

Photos:
Featured Audio: Courtesy & Copyright Patrick Kelly, Bird Sounds Courtesy & Copyright Kevin Colver and Water at end Courtesy FreeSound.org, Sclolex, contributor
Text: Mary Heers, https://cca.usu.edu/files/awards/art-and-mary-heers-citation.pdf
Additional Reading: Lyle Bingham, https://bridgerlandaudubon.org/

Additional Reading

Wild About Utah, Mary Heers’ Postings

Boling, Josh, Karst Topography, Wild About Utah, November 23, 2o2o, https://wildaboututah.org/karst-topography/

“It is a karst limestone cave, formed from ground water flowing through limestone and carving sink-holes and underground waterways.”
Minnetonka Cave, USDA Forest Service, US Department of the Interior, https://www.fs.usda.gov/recarea/ctnf/recarea/?recid=70736

Minnetonka Cave Brochure, USDA Forest Service, US Department of the Interior, 23.308.415.04/04, https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_015684.pdf

History of Minnetonka Cave, The Herald Journal, August 6, 2020, https://www.hjnews.com/bear_laker/history-of-minnetonka-cave/article_950c5030-d82d-11ea-9bf1-47556f110eed.html

Davis, Jim and Milligan, Mark, Why is Bear Lake so Blue? and other commonly asked questions, Public Information Series 96, Utah Geological Survey, Department of Natural Resources, 2011, https://ugspub.nr.utah.gov/publications/public_information/pi-96.pdf

Posted on

Bats and Echolocation

Bats and Echolocation: Little Brown Bats, Courtesy U.S. Fish and Wildlife Service, Photographer: W.D. Fritzwater
Little Brown Bats
Photographer: W.D. Fritzwater
Courtesy US FWS

Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

There are approximately 4600 mammal species in the world. A fifth—yes, 20%– of these species are bats. They are found everywhere except Antarctica. In Utah they are found at every elevation and in every ecosystem.

Bats are the only mammal that flies. “You forgot about humans,” my very precise husband points out. Well, OK bats are the only mammal that flies without a license and an airplane.

The majority of bats have smallish eyes perhaps leading to the expression “blind as a bat.” But bats are not at all blind. All of them can see and some rely solely on vision for both navigation and foraging. But most bats also have a sixth sense—called echolocation–to navigate and detect prey.

Mariana Fruit Bat
From the
Northern Mariana Islands
Photographer: Ann Hudgins
Courtesy US FWS

Echolocation refers to the process of sending out pulses of sound and listening to
the echoes to locate or avoid objects. Bats emit pulses of high frequency sound from their larynx or voicebox. These sounds are ultrasonic which means that they occur at frequencies beyond the range that humans can hear. The sounds are emitted through the mouth in some bats and through the nose in others.

The sounds bounce off external objects and echoes are returned to the bat’s ear. The size and shape of the bat’s ears help amplify the returning sound. The sound travels through the ear and is converted to vibrations in the inner ear fluid and then on to the brain via the auditory nerve.

Bat brains have unique structures that compare the features of the original sound pulse against the characteristics of the returning echoes. By assembling and assessing the return data, bats can know the direction of and distance of an object. Some bat species have evolved echolocation to such a degree that they can even distinguish shape among individual species of insects.

Townsend’s Big-eared Bat
Courtesy National Park Service

Because of echolocation bats are phenomenal hunters in low light conditions. A single little brown bat can catch 300 to 3,000 insects per night, and a nursing mother little brown bat eats more than her body weight each night — up to 4,500 insects. Hmm. That’s a lot of mosquitoes. I think I’ll invite some bats to my backyard this summer.

Thanks to the Marie Eccles Foundation –the Russell Family for supporting Stokes Nature Center programs.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:
Images: Courtesy US FWS and USDA Forest Service
Text: Stokes Nature Center: Holly Strand

Sources & Additional Reading

Bat Conservation International. 1997. Bat Chat: An Introduction to Echolocation
https://www.batcon.org/, https://www.batcon.org/resources/media-education/learning/bat-squad/bat-squad-ep-4-bat-chat-join-the-bat-squad

Wilson, Don E. 1997 Bats in Question: The Smithsonian Answer Book. Smithsonian Institution Press, Washington, DC https://www.amazon.com/Bats-Question-Smithsonian-Answer-Book/dp/1560987391

Bats Live, Prince William County Public Schools, Manassas, VA, https://batslive.pwnet.org/

Bat Week 2015
Sometimes misunderstood, bats are important and fascinating animals. Watch this video to learn some bat facts, find out what challenges are facing bats today and what you can do to help #savethebats.
Bat Week Video from USGS, US FWS and The Organization for Bat Conservation

13 Facts About Bats, US Department of the Interior, Blog, 10/24/2016, https://www.doi.gov/blog/13-facts-about-bats